package main

import (
	"bytes"
	"fmt"
	"strings"
)

func main() {
	var s1, s2, x1, x2 string
	var p1, p2 []byte

	fmt.Scanln(&s1, &p1, &x1)
	fmt.Scanln(&s2, &p2, &x2)

	l1, l2 := len(p1), len(p2)

	if l1 > l2 {
		p2 = append([]byte(strings.Repeat("0", l1-l2)), p2...)
	} else if l2 > l1 {
		p1 = append([]byte(strings.Repeat("0", l2-l1)), p1...)
	}

	comp := bytes.Compare(p1, p2)
	if comp == 1 {
		fmt.Println(s1)
	} else if comp == -1 {
		fmt.Println(s2)
	} else {
		fmt.Println(-1)
	}
}